1. Field of the Invention
The invention relates to a sintering of the downdraught type, comprising a train of grate cars travelling along support means, e.g. rails. The grate cars are provided with grates to carry material to be sintered. Suction boxes, known as windboxes, are arranged to create a partial vacuum under the grates of the grate cars during operation of suction means, so as to produce a downward draught through the material being sintered.
2. Description of the Prior Art
A machine of this type is known for example from Kawasaki Steel Technical Report No. 15 of October 1986, pages 9 to 15. A problem of this known sintering machine is so-called false air which is sucked along by the fan. False air is understood to be air that is not sucked through the material to be sintered, but for example through the space between the suction boxes and the support means for the train of grate cars as well as through the spaces between the grate cars themselves.
In this prior art article various measures are proposed to reduce the quantity of false air. The sintering machine is provided with one or more bars under each grate car, which bars are urged in the direction of a guideway connected to the fixed structure by spring force. Guideway and bar together provide a gastight seal. This gastight sealing function is usually further supported by applying fat or a plastics material between the bar and the guideway. Nevertheless some leakage is possible via the part situated between the bar and the grate car. As a solution to this, the prior art article mentions the application of a special seal in the space between the bar and the grate car.
In addition to complexity, a disadvantage of the measures mentioned is also the fact that maintaining the gastight seal requires intensive maintenance as a consequence of the strongly abrasive ambient conditions. For this maintenance the grate cars have to be removed wholly.
GB-A-1 146 346 shows a side sealing structure for grate cars in a different form of sintering machine in which air is forced upwardly through the grates from windboxes below them to a collection hood above them. The problems of sealing of the hood to prevent escape of gas, e.g. sulphur dioxide, are obviously different from those of a down-draught sintering machine. A tunnel structure is provided at each side around the wheels of the grate cars, with seals against the grate cars to both the hood space and the space beneath the grates.